1. Field of the Invention
The present invention relates to a storage device, particularly to a wavelength-multiplex and space-multiplex holographic storage device.
2. Description of the Related Art
With the fast increasing amount of information, the capacity of a storage device should also increase as much. However, the capacity of the current optical disc has reached the limit. Therefore, developing higher capacity storage technologies should be the prior task, and the holographic storage technology is a high potential one among them.
Refer to FIG. 1. In one holographic storage technology, a coded signal light beam 14 interferes with a coherent reference light beam 12 to form an interference pattern, and the interference pattern is stored on a holographic disc 10. The signal light beam 14 usually has a single wavelength. If there are several signal light beams, all the signal light beams have only a single wavelength also. The single-wavelength light beams store information on the rotating holographic disc 10. However, the information storage is only two-dimensional. Therefore, such a technology has a lower access rate and a smaller storage capacity. In another holographic storage technology, a frequency-modulation device modulates a signal light beam, and the frequency-modulated light beam is used to store information. However, the access rate is decreased by the frequency-modulation process.
Thus, the present invention proposes a wavelength-multiplex and space-multiplex holographic storage device having a higher access rate and a larger storage capacity to solve the abovementioned problems.